Conventionally, a substrate with the same dimension as a memory card is implemented as a chip carrier in early memory packages such as revealed in U.S. Pat. No. 7,094,633 B2. A plurality of substrates are physically interconnected in a substrate strip, then chips are disposed on the corresponding substrates followed by molding the substrate strip, and finally, the molded substrate strip is singulated into individual memory cards. However, the singluated cut sides of the substrate are exposed from the encapsulant which cause poor moisture resistivity and poor reliability. Moreover, the substrate with the same dimension as the memory card is vulnerable for peeling due to stresses exerted on the peripheries of the memory card.
In order to reduce the packaging cost of memory packages, it has been attempted to replace a substrate by a leadframe as revealed in U.S. Pat. No. 7,488,620 B2 and 6,965,159 B1. A leadframe provides a plurality of leads, a plurality of contact pads, and a plurality of die pads made of metal. However, a leadframe is quite limited in circuitry layout with complicated wire bonding or long bonding wires where RDL may be needed on a chip surface leading to even higher chip fabrication cost. Furthermore, no matter a leadframe or a substrate is implemented as a chip carrier, the cut ends of tie bars of a leadframe or the cut sides of a substrate after singulation would become electrically conductive and exposed to atmosphere leading to ESD issues during packaging processes or end-product implementation.